JP4666192B2 - Developer supply device - Google Patents

Description

  The present invention relates to a developer supply apparatus configured to supply a charged powdery developer to a supply target while being conveyed along a developer conveyance path by an electric field.

  As this type of apparatus, it is disclosed in Japanese Patent Application Laid-Open No. 60-115962, Japanese Patent Application Laid-Open No. 11-84862, Japanese Patent Application Laid-Open No. 2001-209246, Japanese Patent Application Laid-Open No. 2002-287495, Japanese Patent Application Laid-Open No. 2008-152183, and the like. What is being known. Such an apparatus includes a plurality of transport electrodes arranged along the developer transport direction, and is configured to transport the developer by an electric field generated by application of a drive voltage to the plurality of transport electrodes. .

  In this type of apparatus, when the supply state of the developer becomes defective, problems such as disturbance of the formed image occur. The present invention has been made to cope with such a problem. That is, an object of the present invention is to make the supply state of the developer more appropriate.

<Configuration>
The developer supply device that is the subject of the present invention is configured to supply a charged powdery developer to a supply target while being transported along the developer transport path by an electric field.

  The developer supply device includes a transport substrate. The transport substrate includes a plurality of transport electrodes arranged at predetermined intervals along the developer transport path, and the developer transport path is caused by an electric field generated when a voltage is applied to the transport electrodes. The developer is transported along.

  The developer supply device may include a casing and a developer carrying member.

  The casing is a box-like member, has an opening that opens upward toward the supply target, and is configured to store the developer in a developer storage section at the bottom. In this case, the casing supports the transfer substrate on its inner wall surface.

  The developer carrying member is a roller-shaped member having a cylindrical surface, and is provided to face the supply target and the transport substrate. Specifically, the developer carrying member is provided so as to face the supply target while being accommodated inside the casing so as to face the opening.

  The transfer board includes an upper transfer board and a bottom transfer board. Here, the transport substrate has a position in the triboelectric charge train of the material constituting the surface of the upper transport substrate, and the same polarity side as the charge polarity of the developer than the material constituting the surface of the bottom transport substrate. Can be configured.

  The upper transport substrate is a plate-shaped rigid substrate, and is erected so as to transport the developer upward. Specifically, for example, the upper conveyance substrate conveys the developer upward toward the developer carrying member (conveys the developer vertically upward to a position facing the developer carrying member). )

  The bottom conveyance substrate is a flexible substrate, and is curved in a semicircular arc shape in a side sectional view so as to constitute a bottom surface of the developer storage portion. The bottom transport substrate is configured to charge the developer by friction with the developer, and the lower end portion so as to transport the charged developer toward the lower end portion of the upper transport substrate. Connected with.

  A feature of the present invention is that the upper transport is performed so that a connecting portion which is an end of the bottom transport substrate connected to the lower end of the upper transport substrate transports the developer in the same direction as the lower end. It is superimposed on the lower end of the substrate. In addition, the connection portion includes the one at the most upstream position in the developer transport direction among the transport electrodes arranged along the developer transport path at the lower end portion of the upper transport substrate, and the connection portion. The distance between the transport electrodes arranged along the developer transport path and the most downstream position in the direction is equal to or less than the predetermined distance in the direction. It can be overlaid with the lower end.

  In addition, the connection portion in the bottom transport substrate may be overlapped with a lowermost region in which the transport electrode is not provided in the lower end portion of the upper transport substrate.

  The developer supply device may further include an upper transport substrate driving unit and a bottom transport substrate driving unit. The upper transport substrate driving unit is connected to the upper transport substrate and transports the developer on the upper transport substrate (toward a position where the upper transport substrate faces the developer carrying member). The voltage is output. The bottom transport substrate drive unit is connected to the bottom transport substrate and outputs a voltage for transporting the developer more strongly than the upper transport substrate on the bottom transport substrate.

  The developer supply device may further include a developer accumulation eliminating unit for eliminating the accumulation of the developer at the connection portion. Specifically, for example, the developer accumulation eliminating means returns the developer accumulated at the connection portion to the developer storage portion.

<Action and effect>
In this configuration, in the developer stored in the developer storage portion, the bottom contact substrate is in contact with the bottom transport substrate due to the electric field generated in the bottom transport substrate. It is conveyed toward the part. Then, the developer is delivered to the lower end portion of the upper transport substrate from the connection portion of the bottom transport substrate connected to the lower end portion of the upper transport substrate. The upper transport substrate that has received the developer at the lower end transports the developer vertically upward.

  At this time, the connecting portion which is an end portion of the bottom transport substrate connected to the lower end portion of the upper transport substrate transports the developer in the same direction as the lower end portion of the upper transport substrate. Therefore, the developer is smoothly transferred to the upper transport substrate at the connection portion, and the occurrence of the developer deposition at the connection portion is suppressed as much as possible.

  In particular, among the transport electrodes arranged along the developer transport path at the lower end of the upper transport substrate, the one at the most upstream position in the developer transport direction, and the developer at the connection portion The connecting portion of the bottom transport substrate is arranged so that the distance in the direction between the transport electrodes arranged along the transport path and the most downstream position in the direction is equal to or less than the predetermined distance. By overlapping the lower end portion of the upper transport substrate, the developer can be transferred to the upper transport substrate more smoothly at the connection portion.

  In addition, since the connection portion is formed in a curved surface shape, the developer can be transferred from the bottom transport substrate at the lower end of the upper transport substrate more smoothly.

  In addition, by transferring the developer more strongly than the upper transfer substrate on the bottom transfer substrate, the transfer of the developer from the bottom transfer substrate at the lower end portion of the upper transfer substrate is smoother. Can be done.

  As described above, according to the present invention, it is possible to more appropriately supply the developer to the supply target.

1 is a side view showing a schematic configuration of a laser printer as an image forming apparatus to which an embodiment of the present invention is applied. FIG. 2 is an enlarged side sectional view of the toner supply device shown in FIG. 1. FIG. 3 is an enlarged side cross-sectional view of the transport substrate shown in FIG. 2. It is a graph which shows an example of the output waveform of each power supply circuit shown by FIG. It is the sectional side view to which the vicinity of the location (board | substrate junction part) where the connection part of the bottom part conveyance board | substrate shown by FIG. 2 and the lower end part of a perpendicular | vertical conveyance board | substrate were piled up was expanded. FIG. 6 is a side sectional view showing a modification of the configuration of the substrate bonding portion shown in FIG. 5.

  Hereinafter, embodiments of the present invention (embodiments that the applicant considers best at the time of filing of the present application) will be described with reference to the drawings.

  It should be noted that the following description of the embodiment is specific to the extent possible in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in. Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

<Configuration of laser printer>
FIG. 1 is a side view showing a schematic configuration of a laser printer 1 as an image forming apparatus to which an embodiment of the present invention is applied.

  Referring to FIG. 1, the laser printer 1 includes a paper transport mechanism 2, a photosensitive drum 3, a charger 4, a scanner unit 5, and a toner supply device 6.

  Sheet-like paper P is stored in a stacked state in a paper feed tray (not shown) provided in the laser printer 1. The paper transport mechanism 2 is configured to transport the paper P along a predetermined paper transport path PP.

  An electrostatic latent image carrying surface LS is formed on the peripheral surface of the photosensitive drum 3 as a supply target of the present invention. The electrostatic latent image carrying surface LS is formed as a cylindrical surface parallel to the main scanning direction (z-axis direction in the figure). The electrostatic latent image carrying surface LS forms an electrostatic latent image based on a potential distribution, and carries toner T (see FIG. 2) as a developer of the present invention at a position corresponding to the electrostatic latent image. Is configured to do.

  The photosensitive drum 3 is configured to be rotationally driven in a direction indicated by an arrow in the drawing (clockwise in FIG. 1) around a central axis C parallel to the main scanning direction. That is, the photosensitive drum 3 is configured so that the electrostatic latent image carrying surface LS can move along the sub-scanning direction orthogonal to the main scanning direction.

  The charger 4 is disposed so as to face the electrostatic latent image carrying surface LS. The charger 4 is a corotron type or scorotron type charger, and is configured so that the electrostatic latent image carrying surface LS can be uniformly positively charged.

  The scanner unit 5 is configured to generate a laser beam LB modulated based on image data. That is, the scanner unit 5 is configured to generate a laser beam LB having a predetermined wavelength band in which light emission ON / OFF is controlled depending on the presence or absence of pixels.

  Further, the scanner unit 5 is configured to image (expose) the generated laser beam LB at the scan position SP on the electrostatic latent image carrying surface LS. Here, the scan position SP is provided at a position downstream of the charger 4 in the rotation direction of the photosensitive drum 3 (direction indicated by the arrow in FIG. 1: clockwise in the drawing).

  Further, the scanner unit 5 moves (scans) the position where the laser beam LB is imaged on the electrostatic latent image carrying surface LS at a constant speed along the main scanning direction. An electrostatic latent image can be formed on the latent image carrying surface LS.

  The toner supply device 6 as the developer supply device of the present invention is disposed below the photosensitive drum 3 so as to face the photosensitive drum 3. The toner supply device 6 is configured to be able to supply the electrostatic latent image carrying surface LS in a charged state at the developing position DP. Here, the development position DP is a position where the toner supply device 6 faces the electrostatic latent image carrying surface LS. The detailed configuration of the toner supply device 6 will be described later.

  Next, the specific configuration of each part of the laser printer 1 will be described in more detail.

  The sheet transport mechanism 2 includes a pair of registration rollers 21 and a transfer roller 22.

  The registration roller 21 is configured so that the paper P can be sent out between the photosensitive drum 3 and the transfer roller 22 at a predetermined timing.

  The transfer roller 22 is disposed so as to face the electrostatic latent image carrying surface LS, which is the outer peripheral surface of the photosensitive drum 3, with the sheet P interposed therebetween at the transfer position TP. Further, the transfer roller 22 is configured to be rotationally driven in a direction (counterclockwise) indicated by an arrow in the drawing.

  The transfer roller 22 is connected to a bias power supply circuit (not shown). That is, a predetermined transfer bias voltage for transferring the toner (developer) attached on the electrostatic latent image carrying surface LS to the paper P is applied between the transfer roller 22 and the photosensitive drum 3. It has become.

<< Toner Supply Device >>
FIG. 2 is an enlarged side cross-sectional view of the toner supply device 6 shown in FIG. Referring to FIG. 2, the toner supply device 6 is configured to supply the charged toner T to the photosensitive drum 3 while being transported along the toner transport path TTP by an electric field.

  The toner box 61 forming the casing of the toner supply device 6 is a box-like member formed in an oval shape in a side sectional view, and its longitudinal direction is parallel to the vertical direction (y-axis direction in the figure). Is arranged. The toner box 61 contains toner T as a powdery dry developer. That is, the toner storage portion 61 a is formed by the space inside the semi-cylindrical lower end portion of the toner box 61. In this embodiment, the toner T is a positively chargeable, non-magnetic one-component black toner. An opening 61b is provided at the top of the toner box 61, that is, at a position facing the photosensitive drum 3.

  Inside the toner box 61 is housed a developing roller 62 as a developer carrying member of the present invention. The developing roller 62 is rotatably supported by the toner box 61. The developing roller 62 is a roller-like member having a toner carrying surface 62a that is a cylindrical circumferential surface, and is provided to face the photosensitive drum 3 at the opening 61b. That is, the toner box 61 is arranged such that the toner carrying surface 62a of the developing roller 62 is close to the electrostatic latent image carrying surface LS of the photosensitive drum 3 at the developing position DP with a gap of a predetermined interval (about 500 μm). The developing roller 62 is disposed.

  Inside the toner box 61, a transport substrate 63 is provided along the toner transport path TTP. The transport substrate 63 is fixed to the inner wall surface of the toner box 61. In the present embodiment, the transport substrate 63 includes a bottom transport substrate 63a, a vertical transport substrate 63b, and a recovery substrate 63c. The details of the internal configuration of the transfer substrate 63 will be described later.

  The bottom conveyance substrate 63 a is disposed at the bottom in the space inside the toner box 61. Specifically, the bottom conveyance substrate 63a is a flexible substrate, and is curved in a semicircular arc shape and a concave shape in a side sectional view so as to constitute the bottom surface of the toner storage portion 61a. The bottom transport substrate 63a is configured to transport the toner T in the toner reservoir 61a toward the vertical transport substrate 63b.

  The connecting portion 63a1 which is the upper end portion of the bottom transfer substrate 63a on the vertical transfer substrate 63b side is connected to the lower end portion 63b1 of the vertical transfer substrate 63b so as to deliver the toner T during electric field transfer to the lower end portion 63b1 of the vertical transfer substrate 63b. Connected smoothly. That is, the connection portion 63a1 of the bottom conveyance substrate 63a and the lower end portion 63b1 of the vertical conveyance substrate 63b are overlapped with each other so as to convey the toner T in the same direction (that is, vertically upward). Will be described later in detail).

  The vertical conveyance substrate 63b is a flat plate-like rigid substrate, and is erected so as to convey the toner T vertically upward. The vertical transport substrate 63b is configured to transport the toner T delivered from the bottom transport substrate 63a toward the developing roller 62 and the development position DP in the toner transport direction TTD.

  In the present embodiment, the upper end portion of the vertical transport substrate 63b is provided to a position higher than the center of the developing roller 62, specifically, to a position reaching the opening 61b. This upper end is bent into a concave curved surface so as to face the cylindrical toner carrying surface 62a of the developing roller 62 with a gap of a constant interval (about 300 μm).

  The collection substrate 63 c is provided to face the developing roller 62 on the opposite side of the upper end portion of the vertical conveyance substrate 63 b and the developing roller 62. In other words, the collection substrate 63c is disposed downstream of the opening 61b of the toner box 61 in the toner transport direction TTD. In the present embodiment, the end portion of the collection substrate 63c in the toner transport direction TTD is provided at a position corresponding to the lower end of the developing roller 62.

  The collection substrate 63c is configured to collect the toner T that has not been consumed at the development position DP from the development roller 62 and to convey the collected toner T toward the lower toner storage portion 61a. Specifically, the upper part of the collection substrate 63c is opposed to the developing roller 62 with a gap of a certain distance (a gap narrower than the gap between the photosensitive drum 3 and the developing roller 62 at the developing position DP: about 300 μm). As shown, it is bent into a concave curved surface. The lower end portion of the collection substrate 63c is provided so as to convey the toner T vertically downward.

  The vertical transfer board 63b is electrically connected to the transfer power supply circuit 64. The transport power supply circuit 64 as the upper transport substrate drive unit of the present invention outputs a voltage for transporting the toner T toward the position where the developing roller 62 and the vertical transport substrate 63b face each other by the vertical transport substrate 63b. It has become.

  The bottom transfer board 63a is electrically connected to the bottom transfer power supply circuit 65. The bottom conveyance power supply circuit 65 as the bottom conveyance substrate drive unit of the present invention has a voltage (that is, amplitude larger than that of the conveyance power supply circuit 64) for conveying the toner T more strongly than the vertical conveyance substrate 63b in the bottom conveyance substrate 63a. A large voltage) is output.

  The recovery board 63c is electrically connected to the recovery power supply circuit 66. The developing bias power supply circuit 67 is electrically connected to the developing roller 62.

  The transport power circuit 64, the bottom transport power circuit 65, the recovery power circuit 66, and the development bias power circuit 67 circulate the toner T in the toner transport direction TTD along the toner transport path TTP (the toner T in the toner storage unit 61a). Is supplied to the developing position DP while being once carried on the developing roller 62, and the toner T that has not been consumed at the developing position DP is collected from the developing roller 62 and returned to the lower toner storage portion 61a). The voltage is output.

  In the space inside the toner box 61, a shielding plate 68 is disposed at a position below the developing roller 62 and close to the vertical conveyance substrate 63b. The shielding plate 68 is provided so that the toner T does not adhere to the developing roller 62 when the toner T rises in the space inside the toner box 61 by the operation of the transport substrate 63.

  An agitator 69 is accommodated at the bottom of the space inside the toner box 61. The agitator 69 is configured such that the tip of the rotary blade slides on the surface of the transport substrate 63. The agitator 69 as the developer accumulation eliminating means of the present invention is rotated about a rotation center axis parallel to the main scanning direction, so that the toner T in the toner storage portion 61a is agitated and is connected to the connection portion 63a1. When the toner T accumulates, the toner T is returned to the toner storage unit 61a.

<<< Transport substrate >>>
FIG. 3 is an enlarged side sectional view of the transfer board 63 shown in FIG.

  Referring to FIG. 3, the transport substrate 63 includes a transport electrode 631, a transport electrode support layer 632, an insulating layer 633, and a cover layer 634.

  The transport electrode 631 (the transport electrode 631 in the bottom transport substrate 63a is referred to as the bottom transport electrode 631a, the transport electrode 631 in the vertical transport substrate 63b is referred to as the vertical transport electrode 631b, and the transport electrode 631 in the recovery substrate 63c is referred to as the recovery electrode 631c). A linear wiring pattern having a longitudinal direction parallel to the main scanning direction (that is, orthogonal to the sub-scanning direction), and is formed of a copper foil having a thickness of about several tens of μm. The plurality of transport electrodes 631 are arranged at predetermined intervals (for example, at 100 μm intervals) along the toner transport path TTP.

  Each of the plurality of transport electrodes 631 arranged along the toner transport path TTP is connected to the same power supply circuit every third. That is, the transfer electrode 631, connected to the power supply circuit VA, the transfer electrode 631, connected to the power supply circuit VB, the transfer electrode 631, connected to the power supply circuit VC, the transfer electrode 631, connected to the power supply circuit VD, and the power supply circuit VA. The transport electrodes 631, the transport electrodes 631, the transport electrodes 631,... Connected to the power circuit VC connected to the power supply circuit VB are sequentially arranged along the toner transport path TTP (note that these are connected. The power supply circuits VA to VD are components of the transport power supply circuit 64 and the recovery power supply circuit 66 in FIG.

  Here, FIG. 4 is a graph showing an example of output waveforms of the power supply circuits VA to VD shown in FIG. In the present embodiment, as shown in FIG. 4, each of the power supply circuits VA to VD is configured to output a drive voltage that is an AC voltage having substantially the same waveform. Further, the power supply circuits VA to VD are configured so that the phases of the waveforms of the voltages generated by the power supply circuits VA to VD are different by 90 °. That is, the voltage phase is delayed by 90 ° in order from the power supply circuit VA to the power supply circuit VD.

  In this way, the transport substrate 63 applies the drive voltage as described above to each transport electrode 631 and generates a traveling-wave electric field along the toner transport path TTP. The toner is transported in the toner transport direction TTD.

  The plurality of transport electrodes 631 includes a transport electrode support layer 632 (the transport electrode support layer 632 in the bottom transport substrate 63a is the bottom support layer 632a, the transport electrode support layer 632 in the vertical transport substrate 63b is the vertical support layer 632b, and the recovery substrate 63c. The transport electrode support layer 632 in FIG. 5 is referred to as a recovery-side support layer 632c).

  The bottom support layer 632a is a flexible film that forms the base material of the flexible substrate, and is made of an insulating synthetic resin such as a polyimide resin. The vertical support layer 632b is made of a glass epoxy thin plate that forms the base material of a rigid substrate. Similar to the bottom support layer 632a, the recovery support layer 632c is a flexible film that forms the base material of the flexible substrate, and is made of an insulating synthetic resin such as polyimide resin.

  The insulating layer 633 is made of an insulating synthetic resin. The insulating layer 633 is provided on the surface of the transport electrode support layer 632 where the transport electrode 631 is provided so as to fill a space between two adjacent transport electrodes 631.

  On the transport electrode 631 and the insulating layer 633, a cover layer 634 (the cover layer 634 in the bottom transport substrate 63a is the bottom cover layer 634a, the cover layer 634 in the vertical transport substrate 63b is in the vertical cover layer 634b, and the recovery substrate 63c). The cover layer 634 is referred to as a collection-side cover layer 634c). That is, the above-described insulating layer 633 is formed so as to cover the transport electrode 631 and the insulating layer 633. The surface of the cover layer 634 is formed as a smooth surface with very few irregularities so that the toner T can be smoothly conveyed.

  In the present embodiment, the vertical cover layer 634b and the collection side cover layer 634c are formed of the same material (polyester). This material is a triboelectric charging material that sets the toner charge amount to an appropriate value, and the position in the triboelectric charging row is on the plus side, that is, the toner T of the material constituting the bottom cover layer 634a (polyimide). Those having the same polarity as the charging polarity are used.

<<<<< Configuration of Substrate Junction >>>>
FIG. 5 is an enlarged side sectional view of the vicinity of the portion (substrate bonding portion) where the connecting portion 63a1 of the bottom transfer substrate 63a and the lower end portion 63b1 of the vertical transfer substrate 63b shown in FIG. .

  Referring to FIG. 5, the connecting portion 63a1, which is the end portion of the bottom transfer substrate 63a connected to the lower end portion 63b1 of the vertical transfer substrate 63b, is parallel to the vertical plane following the lower end portion 63b1 of the vertical transfer substrate 63b. It is formed in a flat plate shape. That is, the connection portion 63a1 is overlapped with the lower end portion 63b1 of the vertical conveyance substrate 63b so that the toner conveyance direction TTDa1 in the connection portion 63a1 is the same direction as the toner conveyance direction TTDb1 in the lower end portion 63b1 of the vertical conveyance substrate 63b. Yes.

  In the present embodiment, the vertical transport electrode 631b is not formed in the lowermost region 63b2 of the vertical transport substrate 63b. That is, the vertical transport electrode 631b is not formed on the back side of the connection portion 63a1 where the bottom transport electrode 631a is formed.

  In the present embodiment, the bottom most downstream electrode 631a1 (the bottom transport electrode 631a formed at the connection portion 63a1 at the most downstream position in the toner transport direction TTD) and the vertical most upstream electrode 631b1 (vertical transport substrate). The distance in the toner transport direction TTDb1 from the vertical transport electrode 631b formed in the lowermost end region 63b2 of the 63b in the toner transport direction TTDb1 is larger than the distance between adjacent vertical transport electrodes 631b. The connection portion 63a1 is overlapped with the lower end portion 63b1 of the vertical transfer substrate 63b so as to be narrowed.

  Specifically, the bottom end region 632b2 (region below the bottom end of the vertical most upstream electrode 631b1) of the vertical support layer 632b corresponding to the bottom end region 63b2 of the vertical transfer substrate 63b is formed thinner than other portions. Has been. That is, in the lowermost end region 63b2 of the vertical transfer substrate 63b, on the side facing the connection portion 63a1, the flat plate portion at the upper end of the bottom support layer 632a in the connection portion 63a1 is engaged with the substrate joint portion. A step portion is formed to make the step as small as possible.

  In this stepped portion, the surface on the side where the bottom transport electrode 631a is formed (electrode forming surface) in the flat plate-shaped portion at the upper end of the bottom support layer 632a in the connection portion 63a1 is perpendicular to the lower end 63b1 of the vertical transport substrate 63b. It is formed so as to substantially coincide with the outer surfaces of the transport electrode 631b and the insulating layer 633 (therefore, a step at the electrode joint portion is formed on the bottom cover layer 634a at a position where the bottom cover layer 634a rides on the vertical cover layer 634b. It is the thickness.)

  Then, due to the arrangement of the bottom most downstream electrode 631a1 and the vertical most upstream electrode 631b1 and the stepped portion as described above, the distance between the centers in the side sectional view of the bottom most downstream electrode 631a1 and the vertical most upstream electrode 631b1 is as follows. The distance between the centers of adjacent vertical transport electrodes 631b in a side sectional view is set to be substantially the same.

<Description of laser printer operation>
Next, an outline of the operation of the laser printer 1 configured as described above will be described together with the operations and effects of the configuration of the embodiment with reference to the drawings as appropriate.

<< Paper feeding action >>
First, referring to FIG. 1, the leading edge of the paper P stacked on the paper feed tray (not shown) is sent to the registration roller 21. The registration roller 21 corrects the skew of the paper P and adjusts the conveyance timing. Thereafter, the paper P is fed to the transfer position TP.

<< Carrying of toner image on latent image forming surface >>
As described above, while the paper P is being conveyed toward the transfer position TP, an image of the toner T is carried on the electrostatic latent image carrying surface LS that is the circumferential surface of the photosensitive drum 3 as follows. Is done.

<<< Formation of electrostatic latent image >>>
First, the electrostatic latent image carrying surface LS of the photosensitive drum 3 is uniformly charged to the positive polarity by the charger 4.

  The electrostatic latent image carrying surface LS charged by the charger 4 is opposed to the scanner unit 5 (opposite) by the rotation of the photosensitive drum 3 in the direction (clockwise) indicated by the arrow in the drawing. It moves along the sub-scanning direction to a certain scanning position SP.

  At this scan position SP, the laser beam LB modulated based on the image information is applied to the electrostatic latent image carrying surface LS while being scanned along the main scanning direction. Depending on the modulation state of the laser beam LB, a portion where the positive charges on the electrostatic latent image carrying surface LS disappear is generated. As a result, an electrostatic latent image having a positive charge pattern (image-like distribution) is formed on the electrostatic latent image carrying surface LS.

  The electrostatic latent image formed on the electrostatic latent image carrying surface LS is moved to the developing position DP facing the toner supply device 6 by the rotation of the photosensitive drum 3 in the direction indicated by the arrow (clockwise) in the drawing. Move towards.

<<< Conveyance and supply of charged toner >>>
Referring to FIGS. 2 and 3, the toner T stored in the toner box 61 is charged by contact with the bottom cover layer 634a on the bottom transport substrate 63a, friction, or the like. The charged toner T that is in contact with or close to the bottom cover layer 634a on the bottom transport substrate 63a is transported in the toner transport direction TTD by the electric field generated by the voltage applied to the bottom transport electrode 631a, and is perpendicular to the connecting portion 63a1. It is delivered to the transfer board 63b.

  The vertical transport substrate 63b transports the toner T transferred from the bottom transport substrate 63a at the lower end 63b1 vertically upward. At this time, the vertical cover layer 634b in the vertical transport substrate 63b is different from the bottom cover layer 634a in the bottom transport substrate 63a in that the function of further positively charging the positively charged toner T being transported is low. Therefore, a change in the charged state of the developer during conveyance on the vertical conveyance substrate can be suppressed as much as possible.

  Here, the toner T delivered from the bottom conveyance substrate 63a is mixed with toner having a poor charged state (reverse polarity, that is, negatively charged or non-charged). However, in the configuration of the present embodiment, the positively charged toner T is transferred to the developing roller by the electric field formed between the vertical conveying substrate 63b and the developing roller 62 when being conveyed vertically upward by the vertical conveying substrate 63b. When the toner T is carried on the toner 62, the toner T in a poorly charged state falls downward from the vertical transport substrate 63b due to the action of gravity or the electric field described above.

  Thereby, only the toner T having a good charged state is selectively conveyed toward the developing roller 62 and the developing position DP. That is, on the vertical conveyance substrate 63b, the toner T having a good charge state and a poor one are well selected.

  As described above, the positively charged toner T is supplied to the development position DP. The electrostatic latent image formed on the electrostatic latent image carrying surface LS is developed with the toner T in the vicinity of the development position DP. That is, the toner T adheres to the portion on the electrostatic latent image carrying surface LS where the positive charge in the electrostatic latent image has disappeared. As a result, an image of toner T (hereinafter referred to as “toner image”) is carried on the electrostatic latent image carrying surface LS.

  The toner T on the toner carrying surface 62a that has passed through the development position DP (not consumed at the development position DP) moves to the collection substrate 63c side by the action of the collection bias described above. That is, the toner is recovered from the toner carrying surface 62a by the recovery substrate 63c.

  Here, in the present embodiment, an AC recovery bias is applied to the developing roller 62. The toner T in the vicinity of the toner carrying surface 62a of the developing roller 62 vibrates by the action of the AC component of the recovery bias. Due to this vibration, the toner T floating from the toner carrying surface 62a collides with the toner T carried (attached) on the toner carrying surface 62a. Due to such a collision, the toner T carried on the toner carrying surface 62a is likely to float from the toner carrying surface 62a.

  In the present embodiment, the average potential (0 V) of the recovery bias is set to a potential lower than the potential (240 V) of the exposed portion where the toner T is to be supplied on the electrostatic latent image carrying surface LS. Further, in the present embodiment, the electric field between the developing roller 62 and the collection substrate 63c is stronger than the electric field between the developing roller 62 and the photosensitive drum 3.

  Due to such a recovery bias, the toner T that has not been consumed from the portion of the toner carrying surface 62a that has passed through the development position DP is peeled off satisfactorily and moves toward the recovery substrate 63c. Therefore, the occurrence of ghost in the formed image is suppressed as much as possible.

  In the present embodiment, the amplitude of the recovery bias is set larger than the amplitude of the voltage applied to the recovery electrode 631c. For this reason, the recovery operation of the toner T from the toner carrying surface 62a as described above can be performed satisfactorily without increasing the voltage between the adjacent recovery electrodes 631c. Therefore, the insulation between the adjacent recovery electrodes 631c in the recovery substrate 63c can be ensured satisfactorily.

  Further, this recovery bias also serves as a bias for so-called jumping development at the development position DP. Accordingly, the recovery bias can be satisfactorily applied with a simple device configuration.

  The toner T that has moved from the toner carrying surface 62a to the collection substrate 63c is conveyed toward the lower toner reservoir 61a by an electric field generated by a voltage applied to the collection electrode 631c.

  Here, in the present embodiment, the frequency of the recovery bias is set to an integral multiple of the frequency of the voltage applied to the vertical transport electrode 631b and the recovery electrode 631c. Thereby, the recovery bias and the electric field for transporting the toner T on the recovery substrate 63c are well synchronized.

  The toner T is conveyed vertically downward at the lower end of the collection substrate 63c. At this time, the inertia in the same direction as the gravity acts on the toner T. Then, below the lower end portion of the collection substrate 63c, the toner T falls to the toner storage portion 61a by the action of gravity and inertia in the same direction as the gravity. Therefore, even if the collection substrate 63c is not provided until the toner storage portion 61a is reached, the toner T is favorably returned to the toner storage portion 61a.

<< Transfer of toner image from latent image forming surface to paper >>
Referring to FIG. 1, the toner image carried on the electrostatic latent image carrying surface LS of the photosensitive drum 3 as described above has a direction in which the electrostatic latent image carrying surface LS is indicated by an arrow in the drawing. By being rotated (clockwise), the sheet is conveyed toward the transfer position TP. At the transfer position TP, the toner image is transferred onto the paper P from the electrostatic latent image carrying surface LS.

<Effects of Configuration of Embodiment>
In the present embodiment, the connecting portion 63a1 which is the downstream end of the bottom transport substrate 63a in the toner transport direction TTD at the joint between the bottom transport substrate 63a and the vertical transport substrate 63b is the lower end of the vertical transport substrate 63b. The toner T is conveyed in the same direction as the portion 63b1. At this time, the toner T is transported more strongly at the connection portion 63a1 on the bottom transport substrate 63a than at the lower end portion 63b1 of the vertical transport substrate 63b.

  Further, as shown in FIG. 5, the interval between the bottom most downstream electrode 631a1 and the vertical most upstream electrode 631b1 in the toner conveying direction TTD (TTDb1) is smaller than the interval between adjacent vertical conveying electrodes 631b. Yes. Further, the vertical transport electrode 631b is not formed on the back side of the connection portion 63a1 where the bottom transport electrode 631a is formed.

  In addition, since the lowermost end region 632b2 of the vertical support layer 632b is formed thinner than the other portions, the level difference at the junction between the bottom transport substrate 63a and the vertical transport substrate 63b is small.

  According to the configuration of the present embodiment, the transfer of the toner T to the lower end portion 63b1 of the vertical transfer substrate 63b at the connection portion 63a1 of the bottom transfer substrate 63a can be performed smoothly. Therefore, according to the configuration of the present embodiment, the supply state of the toner T with respect to the photosensitive drum 3 is set more appropriately, so that a good image can be formed by the laser printer 1.

  Further, according to the configuration of the present embodiment, the toner T hardly accumulates at the connection portion 63a1. However, when the toner T is accumulated at the connection portion 63a1, the accumulated toner T is scraped off by the agitator 69 and returned to the toner storage portion 61a.

<List of examples of modification>
Note that, as described above, the above-described embodiments are merely examples of typical embodiments of the present invention that the applicant has considered to be the best at the time of filing of the present application. Therefore, the present invention is not limited to the above-described embodiment. Therefore, it goes without saying that various modifications can be made to the above-described embodiment within the scope not changing the essential part of the present invention.

  Hereinafter, some typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for members having the same configuration and function as those described in the above embodiment. And about description of this member, the description in the above-mentioned embodiment shall be used in the range which is not technically consistent.

  Needless to say, the modifications are not limited to those listed below. In addition, a plurality of modified examples can be applied in a composite manner as appropriate within a technically consistent range.

  The present invention (especially those expressed in terms of action and function in each component constituting the means for solving the problems of the present invention) is based on the description of the above embodiment and the following modifications. It should not be interpreted in a limited way. Such a limited interpretation, while improperly harming the applicant's interests (rushing to file under an earlier application principle), improperly imitates the patent for the protection and use of the invention Contrary to the purpose of the law, it is not allowed.

  (1) The application target of the present invention is not limited to a monochromatic laser printer. For example, the present invention can be suitably applied to a so-called electrophotographic image forming apparatus such as a color laser printer or a monochromatic and color copying machine. At this time, the shape of the photosensitive member may not be a drum shape as in the above-described embodiment. For example, a flat plate shape or an endless belt shape may be used. Further, as the exposure light source, other than the laser scanner (LED, EL (electroluminescence) element, phosphor, etc.) can be suitably used.

  Alternatively, the present invention is also suitably applied to an image forming apparatus of a system other than the above-described electrophotographic system (for example, a toner jet system that does not use a photoreceptor, an ion flow system, a multi-stylus electrode system, etc.). obtain.

  (2) The photosensitive drum 3 and the developing roller 62 may be in contact with each other.

  (3) The voltage applied to the developing roller 62 may be only a direct current component (including ground).

  (4) Referring to FIG. 4, the waveform of the voltage generated by each of the power supply circuits VA to VD may be an arbitrary waveform such as a sine wave shape or a triangular wave shape other than a rectangular wave shape.

  In the above-described embodiment, four power supply circuits VA to VD are provided, and the phases of the voltages generated by the power supply circuits VA to VD are different by 90 °. However, the present invention is not limited to this, and for example, three power supply circuits may be provided, and the phases of the voltages generated by the respective power supply circuits may be different by 120 °.

  (5) The configuration of the transport substrate 63 is not limited to that of the above-described embodiment.

  For example, the vertical transfer substrate 63b may be erected substantially along the vertical direction, and may be slightly inclined. Similarly, the lower end portion of the collection substrate 63c may be slightly inclined.

  The central portion of the bottom transfer substrate 63a may be flat.

  The end portion of the collection substrate 63c in the toner conveyance direction TTD may be connected to the bottom conveyance substrate 63a.

  As shown in FIG. 6, the cover layer 634 can be integrally formed on the bottom transfer substrate 63a and the vertical transfer substrate 63b. In this case, the electrode forming surface of the bottom support layer 632a in the connection portion 63a1 and the electrode forming surface of the vertical support layer 632b in the lower end portion 63b1 of the vertical transport substrate 63b coincide with each other in the lowest end region 632b2 of the vertical support layer 632b. By setting the thickness, it is possible to eliminate almost any step in the substrate bonding portion.

  Alternatively, the cover layer 634 can be omitted.

  (6) The shielding plate 68 can be omitted.

  (7) Other modifications not specifically mentioned are naturally included in the technical scope of the present invention within the scope not changing the essential part of the present invention.

  In addition, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function. Furthermore, the contents (including the specification and drawings) of each publication cited in the present specification may be incorporated as part of the specification.

DESCRIPTION OF SYMBOLS 1 ... Laser printer 2 ... Paper conveyance mechanism 21 ... Registration roller 22 ... Transfer roller 3 ... Photosensitive drum (supply object)
4 ... Charger 5 ... Scanner unit 6 ... Toner supply device (developer supply device)
61 ... Toner box (casing)
61a ... Toner reservoir (developer reservoir)
61b ... Opening 62 ... Developing roller (developer carrying member)
62a ... toner carrying surface 63 ... transfer board 63a ... bottom transfer board 63a1 ... connection part 63b ... vertical transfer board (upper transfer board)
63b1 ... lower end 63b2 ... bottom end region 63c ... recovery substrate 631 ... transfer electrode 631a ... bottom transfer electrode 631a1 ... bottom most downstream electrode 631b ... vertical transfer electrode 631b1 ... vertical most upstream electrode 631c ... recovery electrode 632 ... transfer electrode support layer 632a ... bottom support layer 632b ... vertical support layer 632c ... recovery side support layer 633 ... insulating layer 634 ... cover layer 634a ... bottom cover layer 634b ... vertical cover layer 634c ... recovery side cover layer 64 ... transport power supply circuit 65 ... bottom transport power supply circuit 66 ... Recovery power supply circuit 67 ... Development bias power supply circuit 68 ... Shield plate 69 ... Agitator C ... Center axis DP ... Development position LB ... Laser beam LS ... Electrostatic latent image carrying surface P ... Paper PP ... Paper transport path SP ... Scanning position T ... Toner TP ... Transfer position TTD ... Toner Transport direction (developer conveying direction)
TTP ... Toner transport path (Developer transport path)

Japanese Patent Application Laid-Open No. 60-115962 Japanese Patent Laid-Open No. 11-84862 JP 2001-209246 A JP 2002-287495 A JP 2008-152183 A

Claims (14)

In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along the developer transport path by an electric field.
A box-shaped casing having an opening portion that opens upward toward the supply target and configured to store the developer in a developer storage portion at the bottom;
A roller-shaped member having a cylindrical peripheral surface, the developer carrying member provided facing the supply target while being accommodated inside the casing so as to face the opening;
A plurality of transport electrodes arranged at predetermined intervals along the developer transport path are provided, and the developer is transported along the developer transport path by an electric field generated when a voltage is applied to these transport electrodes. A transport substrate, which is configured as described above and supported by the inner wall surface of the casing;
With
The transfer substrate is
An upper transport substrate composed of a plate-shaped rigid substrate, which is erected so as to transport the developer upward toward the developer carrying member;
The developer is charged by friction with the developer, and connected to the lower end so as to convey the charged developer toward the lower end of the upper transport substrate, and the bottom surface of the developer reservoir A bottom transfer substrate made of a flexible substrate curved in a semicircular arc when viewed from the side cross-section,
With
A connection part which is an end part of the bottom part transport board connected to the lower end part of the upper transport board,
To transport the developer in the same direction as the lower end,
In addition, among the transport electrodes arranged along the developer transport path at the lower end portion of the upper transport substrate, the one at the most upstream position in the developer transport direction and the developer transport at the connection portion Among the transport electrodes arranged along the path, the distance in the direction with the most downstream position in the direction is not more than the predetermined distance.
A developer supply device, wherein the developer supply device is overlapped with the lower end portion of the upper transport substrate. The developer supply device according to claim 1,
The developer supply device according to claim 1, wherein the connection portion of the bottom transport substrate is overlapped with a lowermost region of the lower transport substrate where the transport electrode is not provided. The developer supply device according to claim 1 or 2,
The transfer substrate is
The position of the material constituting the surface of the upper transport substrate in the triboelectric charge train is configured to be on the same polarity side as the charge polarity of the developer relative to the material constituting the surface of the bottom transport substrate. A developer supply device characterized by the above. The developer supply device according to any one of claims 1 to 3,
An upper transport substrate driving unit that is connected to the upper transport substrate and outputs a voltage for transporting the developer toward a position facing the developer carrying member on the upper transport substrate;
A bottom transport substrate driving unit connected to the bottom transport substrate and outputting a voltage for transporting the developer more strongly than the upper transport substrate at the bottom transport substrate;
A developer supply apparatus, further comprising: A developer supply device according to any one of claims 1 to 4, wherein
The developer supply apparatus according to claim 1, wherein the upper transport substrate is provided so as to transport the developer vertically upward to a position facing the developer carrying member. The developer supply device according to any one of claims 1 to 5,
A developer supply apparatus, further comprising developer accumulation elimination means for returning the developer accumulated at the connection portion to the developer storage portion. In the developer supply apparatus configured to supply the charged powdery developer to the supply target while being transported along the developer transport path by an electric field.
A plurality of transport electrodes arranged at predetermined intervals along the developer transport path, and the developer along the developer transport path by an electric field generated in response to voltage application to the transport electrodes. Comprising a transport substrate configured to transport
The transfer substrate is
A flat upper transport substrate made of a rigid substrate, which is erected so as to transport the developer upward;
The developer is charged by friction with the developer, and connected to the lower end so as to convey the charged developer toward the lower end of the upper transport substrate, and the bottom surface of the developer reservoir is A bottom conveyance substrate made of a flexible substrate curved in a semicircular arc when viewed from the side cross-section, provided to configure;
With
A connecting portion, which is an end portion of the bottom transfer substrate connected to the lower end portion of the upper transfer substrate, and the lower end portion of the upper transfer substrate so as to transfer the developer in the same direction as the lower end portion. A developer supply device, wherein the developer supply devices are superposed. The developer supply device according to claim 7,
The connecting portion in the bottom transport substrate is
Of the transport electrodes arranged along the developer transport path at the lower end portion of the upper transport substrate, the one at the most upstream position in the developer transport direction and the connection section to the developer transport path The distance in the direction between the transport electrodes arranged along the most downstream position in the direction is equal to or less than the predetermined distance.
A developer supply device, wherein the developer supply device is overlapped with the lower end portion of the upper transport substrate. The developer supply device according to claim 7 or 8,
The developer supply device according to claim 1, wherein the connection portion of the bottom transport substrate is overlapped with a lowermost region of the lower transport substrate where the transport electrode is not provided. A developer supply device according to any one of claims 7 to 9,
The transfer substrate is
The position of the material constituting the surface of the upper transport substrate in the triboelectric charge train is configured to be on the same polarity side as the charge polarity of the developer relative to the material constituting the surface of the bottom transport substrate. A developer supply device characterized by the above. The developer supply device according to any one of claims 7 to 10,
An upper transport substrate driving unit connected to the upper transport substrate and outputting a voltage for transporting the developer on the upper transport substrate;
A bottom transport substrate driving unit connected to the bottom transport substrate and outputting a voltage for transporting the developer more strongly than the upper transport substrate at the bottom transport substrate;
A developer supply apparatus, further comprising: A developer supply device according to any one of claims 7 to 11,
The developer supply apparatus, wherein the upper transport substrate is provided so as to transport the developer vertically upward. The developer supply device according to any one of claims 7 to 12,
A box-shaped casing having an opening opening upward toward the supply target;
The developer supply device, wherein the transport substrate is supported by an inner wall surface of the casing. The developer supply device according to any one of claims 7 to 13,
A developer supply apparatus, further comprising developer accumulation eliminating means for eliminating the accumulation of the developer at the connection portion.

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